Mare Island refers to an island which is part of Vallejo. It is said to be named after a prized white mare owned by Gen. Mariano Guadalupe Vallejo. On an occasion when a number of the General's horses were being ferried across the Strait from the Contra Costa shore to Benicia, the crude barge capsized. Some of the horses swam ashore, others drowned, and the white mare disappeared. It is recorded that many weeks afterward, the white mare was discovered grazing on the hillside of the island across the channel from Vallejo. From that day, the island was known as "Mare's Island," shortened to Mare Island.
Mare Island was a naval base from 1853 to 1996 primarily focused on naval ship construction. The first prototype aircraft carrier was built there as well as the first nuclear powered submarine built on the west coast.